DOCSLIB.ORG

Broker Revisited

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Broker Revisited Broker Revisited Michael Kircher, Klaus Jank, Christa Schwanninger, Michael Stal {Michael.Kircher,Klaus.Jank,Christa.Schwanninger, Michael.Stal}@siemens.com Markus Voelter [email protected] Copyright © 2004, Kircher, Voelter, Jank, Schwanninger, Stal D5-1 After having written the Remoting Patterns book [VKZ04], we felt that it was necessary to take a look at fundamental pattern in that context: Broker of [POSA1]. This revised pattern description reflects the current state of discussion. Main changes are in the responsibilities as well as the participants area of the original Broker pattern: • Finding remote objects has been separated out. Possible solutions therefore are documented as Lookup pattern in [POSA3]. • The original Broker pattern has a Broker participant, which responsibility is the transmission of requests from clients to server, as well as the transmission of responses and exceptions back to the client. This participant has been replaced by a client-side part called Requestor and a server-side part called Invoker. • The original Broker pattern contains a client-side and server-side proxy participant, which encapsulate system-specific functionality such as marshaling of requests and responses and mediation between client and requestor, and invoker and servant, respectively. Broker Revisited replaces these participants by encapsulating their responsibilities within other participants. Proxies are only needed when remote invocations are expected to be invoked as if they were local invocations. As this is not in every known use the case, we made them optional. They are not part of the core responsibility of the Broker Revisited pattern. • Since proxies when needed should be able to be created at runtime, they shouldn’t contain any system-specific functionality. Another reason why client proxies have been made optional is that location transparency is not always necessary. • Broker Revisited focuses on remote communication, host-local communication is only an exception/special-case. • The Bridge participant of the original Broker pattern has been separated out, because interoperability issues such as type system transparency are handled by an appropriate network and marshaling protocol. D5-2 Broker Revisited The Broker Revisited pattern connects clients with remote objects by mediating invocations from clients to remote objects while encapsulating the details of network communication. Example Suppose, you are going to design an innovative framework for home automation where a central network allows to connect different actuators and sensors. The framework should be capable of integrating heterogeneous devices such as VCRs, TVs, notebooks, lighting systems, PDAs, refrigerators, coolers, or security sensors. It provides connectivity using fixed network cables as well as wireless communication lines. External access to the E- Home system is possible via secured Internet access. Central command and control services help to monitor and modify the system’s behavior or malfunctioning. Users and administrators might deploy custom services that leverage multiple devices to allow emerging behavior such as triggering events on one device when other events on different devices occur. Examples could be a recording service where the recording of a television broadcast is triggered by a central clock or the activation of the cooling system by an external telephone call. Services will be implemented by the different vendors of the devices. In order to make all this possible, the services have to collaborate. But the services are located on various controllers in the house, connected through a network between them and software running on those devices. It should be possible to change the collaborations easily and services should not be expected to always run on the same controller. To make the framework successful it is necessary to make it easy for vendors to provide new services quickly, without much overhead in learning how to develope software for the framework. Context A system that consists of multiple distributed objects that need to interact with each other synchronously or asynchronously. Problem Distributed software systems face many challenges that do not arise in single-process software. One major challenge is the communication across unreliable networks. Other challenges are the integration of heterogeneous components into coherent applications, as well as the efficient usage of networking resources. If developers of distributed systems must master all these challenges within their application code, they likely will loose their primary focus: developing application code that resolves their domain-specific responsibilities well. Communication across networks is more complex than local communication, because remote communication concerns have to be considered, e.g. connections need to be established, invocation parameters have to be converted into a network-capable format and transmitted, and a new set of possible errors has to be coped with. This requires handling invocations to local objects differently than invocations of remote objects. Additionally, the tangling of remote communication concerns with the overall application structure complicates the application logic. The following forces must be addressed: • Location Independence—The location of the remote objects should not be hard-wired into client applications. It should be possible to run remote objects on different machines without adaptation of the client's program code. D5-3 • Separation of Concerns—Application logic and remote communication concerns should be well separated to manage complexity and allow for evolution of each concern independent of the other. • Resource Management—Network and other communication resources have to be managed efficiently to minimize footprint and overhead of distributed systems. • Type System Transparency—Differences between type systems should be coped with transparently. • Portability—Platform dependencies should be encapsulated and separated from the application logic. Solution Separate the communication functionality of a distributed system from the application functionality by isolating all communication related concerns. Introduce a client-side requestor and a server-side invoker to mediate invocations between client and remote object. The client-side requestor provides an interface to construct and forward invocations to the server-side invoker. The invoker dispatches incoming requests to the remote object and returns potential results of remote object invocations to the requestor. A marshaler on each side of the communication path handles the transformation of requests and responses from programming-language native data types into a byte array that can be sent across the wire, and vice versa. The details of communication and management of communication resources is hidden from the client and the remote object by the requestor and invoker. Further, the invoker provides a registration interfaces. This allows remote object implementations, so called servants, to be registered and made accessible to clients. Structure The following participants form the structure of the Broker Revisited pattern: A client interacts with a remote object. A requestor forwards requests to an invoker across the network. An invoker invokes requests on a servant. It adapts the interface of the servant, so that the other participants can stay independent of any remote object specifics. Depending on the implementation, this invoker-internal Adapter [GoF] can be decoupled and large parts of the invoker can serve multiple remote objects. A servant implements a remote object the clients wants to use, whereas the remote object may represent an actual object, a component, or a service. A marshaler transforms between invocation parameters/results and a serialized format. D5-4 The following CRC cards describe the responsibilities and collaborations of the participants Class Collaborator Client • Requestor Class Collaborator Requestor • Invoker Responsibility • Marshaler • Invokes remote objects on the requestor • Collects all invocation Responsibility information, such as the • Provides an invocation remote object reference interface, where clients and the invocation can hand over the request parameters, in a request object. object. • Marshals the invocation parameters on invocation, and de-marshal the returned results using the marshaler. Class Collaborator • Uses communication Invoker • Marshaler resources, such as • Requestor network connections, • Servant threads, and possibly manages those. • Sends invocations to Responsibility remote objects, • Allows servants to be respectively the invoker registered. instances they are • Receives requests from the registered with. transport layer. • Hands over the request to • Demarshals request the transport layer. parameters using the • Waits for responses from marshaler, and marshals remote objects and blocks results of the invocation in clients until the result can a response using the be returned. marshaler. • Invokes operations on servants using the request Class Collaborator parameters. Servant • Uses the communication resources and possibly Responsibility manages those. • Implements the remote • Sends responses back to object’s functionality. the requestor. Class Collaborator Marshaler Responsibility • De-/Marshals invocation parameters and results. D5-5 The dependencies between the participants are illustrated by the following class diagram. Marshaler Servant Client serialize () method A () deserialize
Load more

Recommended publications
  • Distributed Objects in C
    Rochester Institute of Technology RIT Scholar Works Theses 2006 Distributed Objects in C# Xiaoyun Xie Follow this and additional works at: https://scholarworks.rit.edu/theses Recommended Citation Xie, Xiaoyun, "Distributed Objects in C#" (2006). Thesis. Rochester Institute of Technology. Accessed from This Master's Project is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. Rochester Institute of Technology Department of Computer Science Master of Science Project Distributed Objects System in C# Submitted By: Xie, Xiaoyun (Sherry) Date: February 2004 Chairman: Dr. Axel T. Schreiner Reader: Dr. Hans-Peter Bischof Observer: Dr. James Heliotis 2 ABSTRACT Today more and more programs run over a collection of autonomous computers linked by a network and are designed to produce an integrated computing facility. Java Distributed Objects (JDO) proposed by Dr. Axel T. Schreiner [1] builds an infrastructure which allows distributed program components to communicate over a network in a transparent, reliable, efficient, and generic way. JDO was originally intended as a teaching device to assess design parameters for distributed objects. This project focuses on porting JDO, which is implemented in Java on Sun’s JDK, to C# on Microsoft’s .NET. On one hand, it builds an infrastructure in C# that simplifies the construction of distributed programs by hiding the distributed nature of remote objects. On the other hand, it generates insights into the differences between two platforms, namely, Java on Sun and C# on .NET, in the distributed objects area.
    [Show full text]
  • Reflective Remote Method Invocation
    Loyola University Chicago Loyola eCommons Computer Science: Faculty Publications and Other Works Faculty Publications 1998 Reflective Remote Method Invocation George K. Thiruvathukal Loyola University Chicago, [email protected] Lovely S. Thomas Andy T. Korczynski Follow this and additional works at: https://ecommons.luc.edu/cs_facpubs Part of the Programming Languages and Compilers Commons Recommended Citation G. Thiruvathukal, L. Thomas, and A. Korczynski, “Reflective Remote Method Invocation,” in ACM Java Grande, 1998. This Conference Proceeding is brought to you for free and open access by the Faculty Publications at Loyola eCommons. It has been accepted for inclusion in Computer Science: Faculty Publications and Other Works by an authorized administrator of Loyola eCommons. For more information, please contact [email protected]. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. Copyright © 1998 George K. Thiruvathukal, Lovely S. Thomas, and A. Korczynski Reflective Remote Method Invocation G. K. Thiruvathukal1 Tools of Computing LLC and Argonne National Laboratory Chicago, Illinois, U.S.A. L. S. Thomas2 Illinois Institute of Technology, Chicago, Illinois, U.S.A. A. T. Korczynski3 Illinois Institute of Technology, Chicago, Illinois, U.S.A. Abstract Remote Method Invocation (RMI) is available in the current Java language design and implementation, providing the much-needed capability of allowing objects running in different Java processes to collaborate using a variation on the popular Remote Procedure Call (RPC). Although RMI provides features which are desirable for high-performance distributed computing, its design and implementation are deficient in key areas of importance to the high-performance computing community in general.
    [Show full text]
  • Websphere Product Family: Overview and Architecture
    Front cover WebSphere Product Family Overview and Architecture Discover the WebSphere family Take an in-depth look at key products Compare capabilities Carla Sadtler Gennaro Cuomo John Ganci Marc Haberkorn Carol Jones Peter Kovari Kevin Griffith Dildar Marhas Rob Will ibm.com/redbooks International Technical Support Organization WebSphere Product Family Overview and Architecture February 2005 SG24-6963-02 Note: Before using this information and the product it supports, read the information in “Notices” on page xv. Third Edition (February 2005) This edition applies to the WebSphere family. © Copyright International Business Machines Corporation 2004, 2005. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . xv Trademarks . xvi Preface . xvii The team that wrote this redbook. xvii Become a published author . xix Comments welcome. xix Summary of changes . xxi February 2005, Third Edition . xxi Chapter 1. IBM WebSphere product overview . xxiii 1.1 WebSphere overview . xxiv 1.2 WebSphere family . xxv 1.3 IBM WebSphere Application Servers . xxvi 1.3.1 WebSphere Application Server V6 for distributed platforms . xxviii 1.3.2 WebSphere Application Server V5.1. xxxi 1.3.3 WebSphere Extended Deployment V5.1 . xxxiii 1.4 IBM software development platform . xxxv 1.4.1 Application development for WebSphere Application Server V6 . xxxvi 1.4.2 WebSphere Studio and Rational Developer . .xxxvii 1.5 IBM WebSphere Business Integration products . .xliii 1.5.1 Integration servers . xlv 1.5.2 Product overview. xlvi 1.5.3 WebSphere Business Integration Server Foundation . xlvi 1.5.4 WebSphere Business Integration Server .
    [Show full text]
  • Remote Procedure Call (RPC)
    Remote Procedure Call (RPC) RPC – RMI - Web Services 1 Complexity of the distributed applications . The programming of distributed applications is difficult. In addition to the usual tasks, programmers who build clients and servers must deal with the complex issues of communication. Although many of the needed functions are supplied by a standard API such as the socket interface, the socket calls require the programmer to specify many low level details as names ,addresses,protocols and ports. Moreover, asinchronous communications models are complex to implement. Distributed implementations tend to use the same standard API (e.g.,the socket interface). As a consequence most of the detailed code found in one program is replicated in others RPC – RMI - Web Services 2 . For example, all client programs that use a connection oriented transport must create a socket, specify the server’s endpoint address, open a connection to the server, send requests,receive responses and close the connection when interaction is complete. Tools (software that generates all or part of a computer program) have been created to construct clients and servers. Tools cannot eliminate all programming: a programmer must supply the code that perform the computation for the particular service. However, a tool can handle the communication details. As a result the code contains fever bugs. RPC – RMI - Web Services 3 . RPC = Remote Procedure Call . The basic model has been proposed by Birrell e Nelson in 1984. The essence of this technique is to allow programs on different machines to interact using simple procedure call/return semantics, just as if the two programs were in the same computer .
    [Show full text]
  • A Comparative Evaluation of .Net Remoting and JAVA RMI Taneem Ibrahim University of Arkansas, Fayetteville
    Inquiry: The University of Arkansas Undergraduate Research Journal Volume 5 Article 12 Fall 2004 A Comparative Evaluation of .net Remoting and JAVA RMI Taneem Ibrahim University of Arkansas, Fayetteville Follow this and additional works at: http://scholarworks.uark.edu/inquiry Part of the Computer and Systems Architecture Commons Recommended Citation Ibrahim, Taneem (2004) "A Comparative Evaluation of .net Remoting and JAVA RMI," Inquiry: The University of Arkansas Undergraduate Research Journal: Vol. 5 , Article 12. Available at: http://scholarworks.uark.edu/inquiry/vol5/iss1/12 This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Inquiry: The nivU ersity of Arkansas Undergraduate Research Journal by an authorized editor of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. Ibrahim: A Comparative Evaluation of .net Remoting and JAVA RMI 86 INQUIRY Volume 5 2004 A COMPARATIVE EVALUATION OF .NET REMOTING ANDJAVARMI By: Taneem Ibrahim Department of Computer Science and Computer Engineering Faculty Mentor: Dr. Amy Apon Department of Computer Science and Computer Engineering Abstract: Introduction: Distributed application technologies such as A distributed system is a collection of loosely coupled Micrososoft.NEJRemoting, and Java Remote Method Invocation processors interconnected by a communication network [8]. (RMI) have evolved over many years to keep up with the From tbe point view of a specific processor in a distributed constantly increasing requirements of the enterprise. In the system, the rest of the processors and their respective resources broadest sense, a distributed application is one in which the are remote, whereas its own resources are local.
    [Show full text]
  • Distributed Objects
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by UCL Discovery Distributed Objects Wolfgang Emmerich Neil Roodyn Dept. of Computer Science Cognitech Ltd University College London City Cloisters, 188-194 Old Street London WC1E 6BT,UK London EC1V 9FR, UK [email protected] [email protected] ABSTRACT be addressed. In addition, any distributed application must This tutorial motivates the need for, and discusses the prin- be tolerant of failures, such as temporarily unreachable com- ciples of object-oriented distribution middleware. We will ponents or network time-outs. Dealing with these issues at give an overview how these principles are supported by the the network operating system layer is overly complicated for major incarnations of object-oriented middleware, the Ob- an application engineer. ject Management Group’s Common Object Request Broker Distribution middleware is layered between network operat- Architecture (CORBA), Microsoft’s Distributed Component ing systems and distributed applications in order to bridge Object Model (DCOM) and Java’s Remote Method Invoca- this gap. Middleware provides the application designer with tion (RMI). We will discuss common design problems that a higher-level of abstraction. Middleware systems imple- occur when building applications using distributed objects ment this higher level of abstraction based on primitives that and present techniques for their solution. are provided by network operating systems. While doing so 1 INTRODUCTION they hide the complexity of using a network operating sys- In a number of domains, such as the financial and telecom- tem from application designers. The idea of middleware is munications sector, applications have to be adapted to evolv- not new.
    [Show full text]
  • Distributed Objects
    Introduction to Distributed Objects The idea of distributed objects is an extension of the concept of remote procedure calls. In a remote procedure call system (Sun RPC, DCE RPC, Java RMI), code is executed remotely via a remote procedure call. The unit of distribution is the procedure / function /method (used as synonyms). So the client has to import a client stub (either manually as in RPC or automatically as in RMI) to allow it to connect to the server offering the remote procedure. Object as Distribution Unit In a system for distributed objects, the unit of distribution is the object. That is, a client imports a ”something” (in Java’s JINI system, it’s called a proxy) which allows the client access to the remote object as if it were part of the original client program (as with RPC and RMI, sort of transparently). A client actually imports a Java class and this becomes part of the set of classes available on the client machine. So, for example, the client can define subclasses of this imported class, overload methods, etc. In addition, distributed object systems provide additional services, like a discovery service that allows clients to locate the objects they need, security services, reliability services, etc. Distributed object technologies: 1. DCOM (Distributed Common Object Model), developed by Microsoft, but also available on other platforms. Built on top of DCE’s RPC, interacts with COM. 2. CORBA (Common Object Request Broker Architecture), defined by the Object Management Group, an industry consortium. CORBA is available for most major operating systems 3. JINI (“Genie,” JINI is not initials — a joke; JINI actually doesn’t stand for anything.) JINI is developed on top of Java.
    [Show full text]
  • Distributed Object Based Systems
    Distributed Systems Distributed Object-Based Systems Björn Franke University of Edinburgh, 2015 OVERVIEW • Basic Concepts • Middleware Technologies • CORBA • DCOM • .NET Remote Procedure Calls/Windows Communication Foundation • Google gRPC BASIC CONCEPTS REMOTE PROCEDURE CALLS (RPC) BASIC CONCEPTS REMOTE PROCEDURE CALLS (RPC) BASIC CONCEPTS MARSHALLING/UNMARSHALLING MIDDLEWARE TECHNOLOGIES HIGH-LEVEL VIEW MIDDLEWARE TECHNOLOGIES SLIGHTLY MORE DETAIL • High-level abstractions & API • Heterogeneity Hidden • Transparent Distribution • General purpose services e.g. directory/naming CORBA COMMON OBJECT REQUEST BROKER ARCHITECTURE • Industry-defined standard for distributed objects • Enables collaboration between systems on different operating systems, programming languages, and computing hardware • Interface definition language (IDL) to specify object interfaces. CORBA then specifies a mapping from IDL to a specific implementation language. • Central: Object request brokers (ORBs) • Application initialises ORB, and accesses an internal Object Adapter, which maintains things like reference counting, object (and reference) instantiation policies, and object lifetime policies. • Object Adapter is used to register instances of the generated code classes (result of compiling the user IDL code, which translates interface definitions into an OS- and language-specific class base for use by the user application). CORBA GLOBAL ARCHITECTURE • The Object Request Broker (ORB) forms the core of any CORBA distributed system. • Horizontal facilities consist
    [Show full text]
  • Distributed Computing Paradigms Distributed Application Paradigms
    Distributed Computing Paradigms Distributed Application Paradigms level of abstraction high object space network services, object request broker, mobile agent remote procedure call, remote method invocation client-server message passing low The Message Passing Paradigm Message passing is the most fundamental paradigm for distributed applications. A process sends a message representing a request. The message is delivered to a receiver, which processes the request, and sends a message in response. In turn, the reply may trigger a further request, which leads to a subsequent reply, and so forth. Process A Process B a message Me ssage passing The Message Passing Paradigm The basic operations required to support the basic message passing paradigm are send, and receive. For connection-oriented communication, the operations connect and disconnect are also required. With the abstraction provided by this model, the interconnected processes perform input and output to each other, in a manner similar to file I/O. The I/O operations encapsulate the detail of network communication at the operating-system level. The socket application programming interface is based on this paradigm. http://java.sun.com/products/jdk/1.2/docs/api/index.html http://www.sockets.com/ The Client-Server Paradigm Perhaps the best known paradigm for network applications, the client-server model assigns asymmetric roles to two collaborating processes. One process, the server, plays the role of a service provider which waits passively for the arrival of requests. The other, the client, issues specific requests to the server and awaits its response. service request a client process a server process Server host a service Client host ..
    [Show full text]
  • Distributed Computing Paradigms
    Distributed Computing Paradigms Mei-Ling Liu Distributed Computing Paradigms, 5/8/2007 M. Liu 1 Paradigms for Distributed Applications Paradigm means “a pattern, example, or model.” In the study of any subject of great complexity, it is useful to identify the basic patterns or models, and classify the detail according to these models. This paper aims to present a classification of the paradigms for distributed applications. Characteristics that distinguish distributed applications from conventional applications which run on a single machine. These characteristics are: w Interprocess communication: A distributed application require the participation of two or more independent entities (processes). To do so, the processes must have the ability to exchange data among themselves. w Event synchronization: In a distributed application, the sending and receiving of data among the participants of a distributed application must be synchronized. Distributed Computing Paradigms, 5/8/2007 M. Liu 2 Abstractions Arguably the most fundamental concept in computer science, abstraction is the idea of detail hiding. To quote David J. Barnes1: We often use abstraction when it is not necessary to know the exact details of how something works or is represented, because we can still make use of it in its simplified form. Getting involved with the detail often tends to obscure what we are trying to understand, rather than illuminate it … Abstraction plays a very important role in programming because we often want to model, in software, simplified versions of things that exist in the real world … without having to build the real things. In software engineering, abstraction is realized with the provision of tools or facilities which allow software to be built without the developer having to be cognizant of some of the underlying complexities.
    [Show full text]
  • Distributed Object Systems
    Distributed Systems Distributed Object-Based Systems Björn Franke University of Edinburgh, 2016 OVERVIEW • Basic Concepts • Middleware Technologies • Apache Ignite (see coursework lecture) • CORBA • DCOM • .NET Remote Procedure Calls/Windows Communication Foundation • Google gRPC BASIC CONCEPTS REMOTE PROCEDURE CALLS (RPC) BASIC CONCEPTS REMOTE PROCEDURE CALLS (RPC) BASIC CONCEPTS MARSHALLING/UNMARSHALLING MIDDLEWARE TECHNOLOGIES HIGH-LEVEL VIEW MIDDLEWARE TECHNOLOGIES SLIGHTLY MORE DETAIL • High-level abstractions & API • Heterogeneity Hidden • Transparent Distribution • General purpose services e.g. directory/naming CORBA COMMON OBJECT REQUEST BROKER ARCHITECTURE • Industry-defined standard for distributed objects • Enables collaboration between systems on different operating systems, programming languages, and computing hardware • Interface definition language (IDL) to specify object interfaces. CORBA then specifies a mapping from IDL to a specific implementation language. • Central: Object request brokers (ORBs) • Application initialises ORB, and accesses an internal Object Adapter, which maintains things like reference counting, object (and reference) instantiation policies, and object lifetime policies. • Object Adapter is used to register instances of the generated code classes (result of compiling the user IDL code, which translates interface definitions into an OS- and language-specific class base for use by the user application). CORBA GLOBAL ARCHITECTURE • The Object Request Broker (ORB) forms the core of any CORBA distributed
    [Show full text]
  • Portable Serialization of CORBA Objects: a Reflective Approach Marc-Olivier Killijian Juan-Carlos Ruiz Jean-Charles Fabre LAAS-CNRS LAAS-CNRS LAAS-CNRS 7, Av
    Portable Serialization of CORBA Objects: a Reflective Approach Marc-Olivier Killijian Juan-Carlos Ruiz Jean-Charles Fabre LAAS-CNRS LAAS-CNRS LAAS-CNRS 7, Av. du Colonel Roche 7, Av. du Colonel Roche 7, Av. du Colonel Roche 31077 Toulouse Cedex 4 (France) 31077 Toulouse Cedex 4 (France) 31077 Toulouse Cedex 4 (France) +33.5.61.33.62.41 +33.5.61.33.69.09 +33.5.61.33.62.36 [email protected] [email protected] [email protected] ABSTRACT resulting from different programming languages. We use in this paper the terms portable and language (and platform) The objective of this work is to define, implement and independent interchangeably. illustrate a portable serialization technique for CORBA objects. We propose an approach based on reflection: through Serialization in a homogeneous environment has been studied open compilers facilities the internal state of CORBA objects quite extensively, e.g. in [1] [2]. This is not the case of is obtained and transformed into a language independent serialization in heterogeneous environments where works like format using CORBA mechanisms. This state can be restored [3] [4] focus on platform interoperability but not on language and used by objects developed using different languages and portability. Our objective in this work is to provide facilities running on different software platforms. A tool was developed to serialize and de-serialize CORBA objects in a portable and applied to a Chat application as a case study. The format. We introduce an abstract model of object state so that a proposed technique is used to exchange state information serialized state is interoperable and portable.
    [Show full text]